1. Field of the Invention
The present invention relates to a floating pier to which a ship or a boat, for example, is anchored and which includes a plurality of pier units formed of a synthetic resin connected to each other. The present invention also relates to such a pier unit.
2. Description of the Related Art
A conventional floating pier 800 will be described with reference to FIGS. 31A and 31B. FIG. 31A is a top view of the floating pier 800, and FIG. 31B is a side view thereof in the direction of arrow M.
As is shown in FIGS. 31A and 31B, the floating pier includes a necessary number of pier units 80 connected to each other in series. Each of the pier units 80 has a length of approximately 10 meters and a width of approximately 2 meters. Each pier unit has connection parts 81 and 82 at two ends thereof in a longitudinal direction. Two pier units 80 are connected to each other by connecting the connection part 81 of one pier unit 80 and the connection part 82 of the other pier unit 80 by a pin 83.
Such a pier unit 80 is difficult to be mechanically produced by a molding apparatus due to the excessive size thereof. Accordingly, a pier unit formed of FRP (fiberglass reinforced plastic) is produced by hand lay-up, end a pier unit formed of concrete is produced by casting. Transportation of such a huge pier unit from the plant to the shore requires heavy machinery.
Another conventional floating pier 900 will be described with reference to FIGS. 32 and 33. FIG. 32 is a side view of the floating pier 900, and FIG. 33 is a partial cross sectional view of the floating pier 900 taken along line XXXIII--XXXIII in FIG. 32.
The floating pier 900 includes a lengthy frame 91 having a substantially C-shaped cross section having a top portion 91a and a bottom portion 91b, a deck 92 provided on the top portion 91a of the frame 91, and a plurality of floats 93 provided on the bottom portion 91b of the frame 91. The deck 92 is secured to the top portion 91a of the frame 91 through a bolt and a nut. A flange 94 of each float 93 is also secured to the bottom portion 91b of the frame 91 through a bolt and a nut.
The frame 91 is generally formed of a highly rigid steel plate, but such a plate may be bent due to a bending stress or the like when being subjected to a strong force generated by rough water.
FIG. 34 shows the distribution of strain generated in the frame 91, the deck 92 and the float 93 when an external force d (FIG. 32) is applied by the water to the frame 91 so as to expand the gap between adjacent floats 93. In FIG. 34, point O is the point at the center of the frame 91 in the vertical direction, where no strain is generated. Area Q indicates a tensile strain generated in the lower portion of the frame 91, and area R indicates a compressive strain generated in the upper portion of the frame 91. Area P indicates a tensile strain generated in the float 93, and area S indicates a compressive strain generated in the deck 92.
As is appreciated from FIG. 34, when the tensile strain Q is generated in the frame 91, the compressive strain S is generated in the deck 92 by the tensile strain Q. In another case, a tensile strain may be generated in the deck 92, and a compressive strain may be generated in the float 93. In either case, if the tensile strain or the compressive strain is larger than the yield strength of the deck 92 and the float 93, the deck 92 and the float 93 are broken.
Still another conventional floating pier 1000 will be described with reference to FIGS. 35A, 35B and 35C. FIG. 35A is a top view of the floating pier 1000, FIG. 35B is a schematic cross sectional view of the floating pier 1000 taken along lines XXXVB--XXXVB in FIG. 35A, and FIG. 35C is a schematic cross sectional of the floating pier 1000 taken along lines XXXVC--XXXVC in FIG. 35A.
The floating pier 1000 includes a reinforcing member 103, a deck 104 provided on a top surface of the reinforcing member 103, floats 101 provided on a bottom surface of the reinforcing member 103 for supplying the floating pier 1000 with buoyancy. The deck 104 includes a plurality of deck members 102 arranged side by side.
In order to prevent someone walking on the floating pier 1000 from slipping caused by rainwater or waves, water is drained through gaps 102a between the deck members 102.
As is illustrated in FIGS. 35B and 35C, water passing through the gaps 102a between the deck members 102 drops on the sea below the pier through the reinforcing member 103 and the floats 101. Where the reinforcing member 103 or the float 101 does not exist below the gap 102a, the water directly drops on the sea below the pier. In other words, after passing through the gap 102a, the water passes through various passages before dropping on the sea below the pier.
In the case where the float 101 has an opening at the top, the water enters the float 101, thus preventing the float 101 from functioning properly. FIG. 36 shows a floating pier 1100 proposed to solve such a problem. A float 111 has an inclined roof. Also, an attaching member 111a for attaching the float 111 to a reinforcing member 113 has holes 111b, through which the water flows down. In FIG. 36, reference numeral 112 denotes deck members for forming a deck, and reference numeral 112a denotes a gap between two adjacent deck members 112.
The floating pier 1100, which has such a complicated structure, is difficult to be molded. Further, since the float 111 has no opening, a ballast for adjusting the center of gravity of the float 111 cannot be put into the float 111. Accordingly, the deck is positioned high above the surface of the sea, which destabilizes the floating pier 1100.